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  1. #1
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    Tune Your Mission Control High Speed Shim Stack: How To Guide: Pics

    ================================================== ===============
    WARNING!
    Im not responsible if you damage your fork through hamfistedness or inexperiance working on suspension
    ================================================== ===============

    Hi all

    I have a 08 Lyrik coil u-turn on my Kona Bass, i love the fork, but i have noticed that i can blow through the travel REALLY easily, and the adjustment knobs seem to have no noticeable effect on the forks performance.

    The goal i wanted to acheive in tuning the highspeed shim stack was to try and retain small bump performance, but try and increase the bottom out resistance.

    This mod is really easy, no special tools are required, and accessing the shims can be done in about 5 mins with practice.

    This guide uses a lyrik mission control damper, and i see no reason why it shouldnt work for a totem. If you do not like the outcome, it is easy to return everything to a factory setting.

    Righto, time to show DA SHIMZ !

    ================================================== ===============
    Only tools required for this mod are as follows:

    > 24mm Socket
    > 4mm hex wrench
    > 1.5mm hex wrench
    > Shifter
    > Rags
    > Digital Vernier Calipers (for measuring the shims)
    > Frosty Beverage (for afterwards of course!)

    STEP 1:
    First, we gotta remove the Mission Control Damper. Make sure that the HSC knob is set at maximum hardness (turned fully right). You can tell if its in the correct position as the blue knob will be raised off the wrench flats.



    STEP 2:
    Next you'll want to take your wrench and tighten it on the LSC Knob, then using a 4mm hex, loosen the floodgate adjuster, then the LSC knob will just lift off.





    Next using you 1.5mm hex wrench, loosen the 2 grub screws holding the HSC knob on, then lift it off. Make sure you put the adjuster knobs in a safe place and dont loose em.



    STEP 3:
    Using your 24mm socket, loosen the Mission control top cap


    Once the threads are disengaged, lift the Mission Control damper out of the stanchion, dont yank it out, rock it gently from side to side and lift it out, a tip is to press the centre bit (where the LSC konb sits) down while you lift it out, as this will drain any oil in the floodgate assembly.



    Lift it out and use a rag to wipe away the residue oil, be very careful not do damage the grey piston glyde ring, i strongly suggest you CAREFULLY remove it and place it in a safe place to ensure you dont damage it



    STEP 4:
    Now that you have completely removed the Mission Control Damper, place it on a clean workbench.


    The shim stack is sandwiched between the flared end of the black tube (which i have pulled back to reveal a little black plate which sits inside the base of the black tube) and the gold piston. When you you adjust the HSC knob to make it harder, this black plate is screwed onto the shims, basically acting as a preload adjuster on them, increasing the HSC.


    Next you are going to want to grip the threaded part of the top cap and the gold piston at the bottom, then turn the piston to the left (left from looking at the bottom of the Mission Control Damper) which will unscrew it.


    You can now access the shim's (SHIMZ! ). The HSC compression shim stack is 3 same sized shims, i dont have any measurements though as my vernier calipers died, if someone could give the measurements id be very grateful.


    Now time to tune. Seeing as i wanted more progressiveness, i used a pyramid (sort off) stack. The 2 shims below the 3 originals are 2 same sized but larger shims which i had from an old roco, as the ID hole is the same (again, sorry i dont have measurements but will post them as soon as i have them.). My stack consisted of using a stock sized base shim with the two larger ones on top, but you may tune to your liking.


    I decided to stick to 3 shims, im not certain if you can add many more as the black preload plate (HSC adjust) may grind on them if there are to many. I also recommend you keep the stock shims separate in a safe place incase you want to return to factory spec.


    Install your shims back onto the piston, make sure you get the orientation correct.


    Then screw the piston back on. This is why it was important to make sure that you turned the HSC to max before working, as this makes sure the piston is screw onto the right depth on the threads.



    Thats it your done! Only thing left to do is to reinstall the gylde ring is you removed it, screw the damper back in and put the knobs on. Now this mode may take a bit of trial and error to get a perfect setting for you. You may have to take the damper apart a couple of times to find the perfect shim setting, but dissassembly gets easier the more you do it. I was extremely lucky that my first stack was near perfect for me and my weight (65kg (metric FTW )) Also you may have to check you oil volume if a large amount of oil spilled when you pulled the damper back. Measurement is 112mL of 5wt oil.


    ================================================== ===============
    Shim Measurements:

    Stock Shims:
    Outer Diameter: 20mm
    Inner Diamter: 8mm
    Thickness: 0.10mm

    Mod Shims:
    Outer Diameter: 21mm
    Inner Diameter: 8mm
    Thickness: 0.15

    ================================================== ===============

    Ride report:

    I have a couple days of riding on this moded fork....
    and all i can say is OMFG! It feels freaken awesome, my first shim stack is bloody perfect. The fork has a plushness that rivals that of my 66, meaning small bumps are almost non exsistant. Then about 3/4 of the way down, the larger shims kick in, significantly increasing the bottom out resistance. After a couple days of drops and jumps, i have only bottomed the fork once (and it was on a VERY scrappy landing)

    The Adjustment knobs also have a MUCH more noticeable effect on the damping, even the LSC feels better, which is odd because the LSC is seperate from the High speed shim stack, oh well i anit complaining . I have noticed that the HSC knob may feel as if its stiffer and grinding a little, but its nothing to worry about, ive turned it about a billion times in the last couple of days and nothing has gone wrong.

    ================================================== ===============

    So in the end, do i like this mod?

    **** YES!

    This fork now rips alot better on my bass as im nolonger bottoming the fork by riding off a step. Ill be posting up more long term riding reports as well as the measurements of the shims i used as soon as i have a working set of vernier calipers.

    Hope you found this little mod useful
    Enjoy!
    Last edited by Nick_M2R; 08-24-2009 at 04:49 PM.

  2. #2
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    Thanks for posting that. I'll keep it in mind if I end up with a Lyrik and it's not Pushed. While I like the 36, there isn't really this level of adjustability, though there is one shim.

    I hope more manufacturers offer shim tuning options.

  3. #3
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    No prob JC, glad to hear you liked it, if you end up getting a Lyrik and tune it, let us know how it goes

  4. #4
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    Yeah, I noticed this too on my Lyric, I'm 145lbs, using the stock red spring, which is rated for a 160lbs. minimum rider. I can still bottom the fork during jumps, even with 8-10 HSC. With my current spring the fork feels a little harsh on choppy terrain. When trail riding I only use 2 clicks of HSC,LSC. Nonetheless I'm still very happy with the fork, just need a softer spring for trail riding.

    Nick - How much do you weigh, and what spring are you using red, yellow?
    Folangag

  5. #5
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    Im 65kg (im in australia, so metric all the way!) and use a stock red spring, gives me perfect sag

  6. #6
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    Cool write up Nick! This sounds like just the mod I've been looking for. I'm 190Lbs.(or should I say 86.18Kg) and even with the firm spring in my Lyrik I experience a lot of pretty harsh bottom out. So if I'm understanding correctly, we're looking for different, or larger OD sizes on the shims with the same thickness?

  7. #7
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    Seriously, did you need to put a disclaimer on this All internet information is to be taken with a grain of salt. I appreciate the documentation of the suspension you have been putting up But I wouldn't hold it against you if I damaged something following your example. What is the world coming to.
    Quote Originally Posted by saturnine
    that's the stupidest idea this side of pinkbike.

  8. #8
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    Excellent documentary and your choice of shims is very educational. Without any experience doing this myself, the "mushroom" stack makes logical sense for better big hit speed sensitivity bringing increased progressive compression, and maintaining milder damping for the more moderate trail riding hits.

    There was a recent post here wondering when there will be PUSH tuning for the Lyrik to gain such a wider range of speed sensitivity for rebound. I wonder if doing a similar "mushroom" stack for the rebound piston would bring similar deep travel rebound increased damping landing jumps, while maintaining faster rebound for more moderate hits when trail riding.

    Replacing a couple shims is a lot less expensive than PUSH tuning for those who are mechanically inclined. Although I know PUSH also sometimes replaces the pistons and seals with better quality and always checks slider bushing and leg alignment and more with their service.

  9. #9
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    Nice one!

    Thanks for posting that up!

    This gives us another fork with tuning options.

    Lyric is on the short list now.

    P

  10. #10
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    Cheers for all the positive responses guys

    Comments like that make me want to post more things like this up (Coming soon will be a DHX Air rebuild Guide )

    Seriously, did you need to put a disclaimer on this All internet information is to be taken with a grain of salt. I appreciate the documentation of the suspension you have been putting up But I wouldn't hold it against you if I damaged something following your example. What is the world coming to.
    Haha Yea i know, i put that warning there for the little kids who are flat out turning a wrench who try to do some stuff to there forks, then screw it up and come crying to me about how i broke their fork

    Excellent documentary and your choice of shims is very educational. Without any experience doing this myself, the "mushroom" stack makes logical sense for better big hit speed sensitivity bringing increased progressive compression, and maintaining milder damping for the more moderate trail riding hits.

    There was a recent post here wondering when there will be PUSH tuning for the Lyrik to gain such a wider range of speed sensitivity for rebound. I wonder if doing a similar "mushroom" stack for the rebound piston would bring similar deep travel rebound increased damping landing jumps, while maintaining faster rebound for more moderate hits when trail riding.

    Replacing a couple shims is a lot less expensive than PUSH tuning for those who are mechanically inclined. Although I know PUSH also sometimes replaces the pistons and seals with better quality and always checks slider bushing and leg alignment and more with their service.
    Cheers for the comments mate
    The mushroom stack was what i was thinking from the start, when i first seen that the shim stack was 3 same sizied shims, it made perfect sense why the fork felt so linear. Because the shims didnt get larger, oil just sort of blew through them, and i reckon thats why the HSC knob had little effect. I thought that adding to larger shims on top of a stock one would give me the damping i was looking for, plush in the first 3/4 travel, then stiffen up towards the bottom, and as i said my dampening is now bang on plus the HSC Knob now feels as if its doing something. As soon as i track down a pair of calipers ill get measurements of the shims i used

    Cool write up Nick! This sounds like just the mod I've been looking for. I'm 190Lbs.(or should I say 86.18Kg) and even with the firm spring in my Lyrik I experience a lot of pretty harsh bottom out. So if I'm understanding correctly, we're looking for different, or larger OD sizes on the shims with the same thickness?
    Yep thats what you want, the shims i used are the same thickness and ID, but larger OD

    Nice one!

    Thanks for posting that up!

    This gives us another fork with tuning options.

    Lyric is on the short list now.

    P
    Cheers Mr. P
    Also thank must goto you, as your TST shim mod was what inspired me to do this, as well as provide alot of info

  11. #11
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    i want to do this mod - where to get these size shims???

    my lyrik (and totem) needs this mod. i'm doing it if i can find the shims. but what size are the shims and where to get them?

  12. #12
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    I dont have exact measurements for the shims, i reused some shims from my old ROCO that died because the ID was the same as the stock ones
    Try MXTech.com for shims

  13. #13
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    You''re a champ. I'm gonna take apart my old mission control and see what goes, if I can find a supplier for da shimz of course!
    ~ Downride and Freehill, nothing else ~

  14. #14
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    Righto people an update

    So far i have one 25km cross country epic and numerous runs on our new DH trail on the moded fork and all i can say is that i am in love! The dampening in this baby is so much better than before. Also nothing broken to report, its solid as a rock

  15. #15
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    This page is definitely getting bookmarked,
    awesome stuff man i appreciate the effort & documentation.

  16. #16
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    I'm confused....are the two shims that you changed the same thickness as the originals, but just larger in diameter?

    Darren

  17. #17
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    Is the Lyrik MC cart the same as what is used in the Totem?

  18. #18
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    Darren: Same thickness, larger OD

    Flip: i dont see why the totem MC would be any different, besides being slightly larger

  19. #19
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    huh.....using a larger OD but the same thickness shouldn't produce any change especially to bottoming resistance because the shims are all bending at the same rate when stacked on top of each other. If you used a separating shim to build a two stage stack you might see something but even then it would be difficult because the shims are under preload from the HS spring and the secondary stack may be pushed into the initial stack when static.

    I'm guessing if you noticed a difference in bottoming control it's coming from a slight increase in oil level in the damper leg which would give you an increase in spring rate at the end of the stroke.

    Darren

  20. #20
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    Darren:
    There isnt any bottoming increase from the oil level, as i havent increased the oil level at oil, might even be a little low as you loose some oil when you remove the damper

    With regard to the shim thickness, truth be told i dont have exact measurements as my calipers have died and wont be able to buy new ones till i got to the city next weekend. As of now ive only used a REALLY old set of micrometer's, but i wouldnt trust the measurements. The new shims maybe a tad thicker, or even still you maybe correct and the BO increase is all in my head, either way it like how the fork feels now, it does have an increase in bottom out aswell as the adjusters now feel as if they are doing something

    I had considered using a two stage stack, but was worried that the HSC preload bolt would start grinding on the shims, as there where only 3 shims in there to begin with, but i may try a bit of fiddling and see what happens

    Also just to clear up in no way do i mean to sound like a prick, i actually appreciate your comments, helps me understand even more about these things and ways to improve it

  21. #21
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    Also just to clear up in no way do i mean to sound like a prick, i actually appreciate your comments, helps me understand even more about these things and ways to improve it
    LOL.....Understood, I actually didn't take it that way.

    As for the shims, the thickness increments are 0.1mm, 0.15mm, and 0.2mm so you'd be able to tell the stiffness difference in your fingers without having to measure them. If you can't feel the difference with your fingers, they're probably the same.

    In thinking about this further, another factor maybe the height that you set the jam nut when reassembling the MC unit. Increasing or decreasing the height of the jam nut would change the static height of the HS circuit therefore influencing the damping range that you get as well as the range that the adjusters are effecting. So, if in reassembling your jam nut height was higher than how it came from the factory, you would experience the increased compression force throughout the entire range. As I sit here typing I also just realized that the jam nut height has an effect on the Floodgate range as well.....so many things to consider!

    Darren.

  22. #22
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    Quote Originally Posted by PUSHIND
    LOL.....Understood, I actually didn't take it that way.

    As for the shims, the thickness increments are 0.1mm, 0.15mm, and 0.2mm so you'd be able to tell the stiffness difference in your fingers without having to measure them. If you can't feel the difference with your fingers, they're probably the same.

    In thinking about this further, another factor maybe the height that you set the jam nut when reassembling the MC unit. Increasing or decreasing the height of the jam nut would change the static height of the HS circuit therefore influencing the damping range that you get as well as the range that the adjusters are effecting. So, if in reassembling your jam nut height was higher than how it came from the factory, you would experience the increased compression force throughout the entire range. As I sit here typing I also just realized that the jam nut height has an effect on the Floodgate range as well.....so many things to consider!

    Darren.
    Haha cheers for that, just didnt want you to think i was being a prick bout it haha

    Yep just check the shims with my fingers in the way you described, the 2 i put in there are definitely stiffer than the stock ones, which feel really flimsy.

    Now that you mentioned it, i agree with you about the jam nut, having it set at a different point would make a difference on when the HSC engages as it changes when the oil hits it right?, i may have set it a wee bit higher

    One bloke on pinkbike said i sould remove the Floodgate base plate from the bottom so i get full use from my mod as MUCH more oil will flow through it, although i dont really want to loose the platform, makes the 25km desert races much more bearable

  23. #23
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    Yep just check the shims with my fingers in the way you described, the 2 i put in there are definitely stiffer than the stock ones, which feel really flimsy.

    Now that you mentioned it, i agree with you about the jam nut, having it set at a different point would make a difference on when the HSC engages as it changes when the oil hits it right?, i may have set it a wee bit higher
    Okay, with that being the case then you've effectively shifted the force curve on compression. The positive is that the increase in compression force will be better for single impacts, the negative being that you'll decrease initial bump sensitivity and cause the fork to be less reactive to impacts such as breaking bumps. This is exactly why we often install new pistons into forks and shocks. It allows us to balance the two by using firmer shimming for control, but different port volume and shape to allow the shims to open more rapidly under bump forces.

    Funny thing is, doing what you're doing is what got me my start more than 20 years ago in a garage in Northern Maine. I'm still playing with the same stuff, just now with the advantage of powerful software programs, on-board data logging, and a suspension dynamometer!

    Best of luck!

    Darren

  24. #24
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    Hey Darren-Totem Service

    Hey Darren!
    Any word on Totem tuning at Push?

  25. #25
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    Thanks Darren! Very interesting analysis. Your years of tweaking shocks is worth every dollar of a PUSH tune, and really much more.

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